Mix the ingredients for the wheat pre-batter and let rise at room temperature for at least 4 hours or overnight. Weigh the 130 g required for the starter, freeze the remaining in portions.
Let the potatoes cool to room temperature and mix with the rest of the ingredients in the food processor on a low setting. Then turn it up and knead everything into a smooth dough. Let rest in the bowl for one hour.
Work the dough on a floured board to create an elongated awakening. To do this, first work the dough into a ball from the outside in, so that it builds up tension. Place the ball with the dough top down and press it flat. Now fold in the dough from above and below and gently press together.
Place the dough to rise on a piece of baking paper, cover with a cloth and leave to rest for another 35–45 minutes.
Preheat the oven to 485 ° F (250 ° C), also preheat the baking sheet. Pull the bread with the paper onto the hot tray and slide it into the oven. Bake for 7 minutes, then reduce the temperature to 390 ° F (200 ° C) and finish baking for another 30 minutes. The finished bread should have a core temperature of 203 - 207 ° F (95–97° C)